The shape is a horizontal line that is rough on the top and rough on the bottom.
The rough edges represent heat. The thought is that bake heats something on the top and bottom. Do ovens really work that way? Not sure. I think my oven only uses the lower element for bake and the upper element for broil. Anyhow, there are many oven bake features - roast, bake, convection bake, broil. Generally the horizontal line with rough top and/or rough bottom edge represent some type of oven heating.
Originally the pointy parts on the top and bottom were more rounded and there was a bigger gap at the base of the points. Switched to a sharper point and closed the inner gap. This update decreases the space for dirt/food to accumulate, improves (IMHO) the rough sensation, and simplifies the cut.